The present invention relates to an improved process for preparing benzenesulfonate salts of the formula (I) EQU RCO.sub.2 PhSO.sub.3 M (I)
from acid chlorides or chloroformates and salts of phenolsulfonic acids in which the reaction is conducted in the presence of a phase transfer catalyst.
U.S. Pat. No. 4,704,236 describes a process for preparing acyloxybenzene sulfonate salts in which an alkali metal phenol sulfonate is reacted with an aliphatic acyl halide at a temperature of from 135.degree. to 180.degree. C. in the presence of an organic solvent. Alkali metal acyloxybenzene sulfonate salts precipitate from the reaction mixture as separable solids. It is stated that the aliphatic acyl halide is preferably a linear aliphatic acyl chloride which contains from 6 to 15 carbon atoms, including specifically the acid chlorides derived from heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid. Where branched chain acyl chlorides are used, no difference in yield is noted whether the solvent is aromatic or aliphatic. However, when linear acyl chlorides are used, it is stated in col. 3., lines 7-13, that a very distinct benefit in yield can be achieved when the reaction is carried out in the presence of an aliphatic hydrocarbon solvent. The mole ratio of acyl chloride to alkali metal phenol sulfonate in the examples varies from about 1.5:1 to 2:1.
European Patent Application 0 148 148 describes a process for preparing sodium alkanoyloxyhalidebenzene sulfonates by reacting substantially solid anhydrous sodium phenol sulfonate with alkanoylhalide at a temperature in the range of 90.degree. to 200.degree. C. in the substantial absence of a solvent or an inert reaction medium.
European Patent Application 0 164 786 describes a process for preparing p-isononanoyloxybenzenesulfonate by reacting isononanoic acid chloride with potassium p-phenolsulfonate in the presence of a solvent, preferably an aromatic hydrocarbon, at a temperature in the range of 80.degree. to 200.degree. C.
U.S. Pat. No. 4,536,314 describes the preparation of branched chain aliphatic peroxyacid bleach precursors, such as, for example, sodium 3,5,5-trimethyl hexanoyloxybenzene sulfonate, which is obtained from the reaction of isononanoyl chloride and anhydrous sodium phenol sulfonate. Example 1 describes the reaction in greater detail. Tetrabutylammonium bromide is added to the reaction mixture as a catalyst, but there is no teaching or explanation as to the need or the desirability for employing a catalyst for this type of reaction. Moreover, the applicability of a catalyst in preparing other than branched chain, i.e., linear, precursors as well as its chemistry are left open to speculation.
Many of the compounds which can be prepared by the process of the present invention are known in the art, especially for their utility as bleach activators. The term "bleach activator" is understood in the art to describe a relatively stable compound which will decompose in water in the presence of a peroxygen to give the corresponding peracid bleaching agent.
The bleach activators which can be prepared by the process of the present invention are described in the references cited above as well as in U.K. Patent Specification No. 864,798, European Patent Application 267,048, European Patent Application 284,292, U.S. Pat. Nos. 4,483,778, 4,536,314, 4,634,551, 4,681,592, 4,778,618 and 4,735,740.